20 or more day cruise to Hawaii/Tahiti

We just returned from Hawaii and now we really want to do another one back there and also combine it with a Tahiti or that area cruise. I have checked just a few places and don't see much offered.
I would like to know your recommendations on when the best weather is and maybe an idea on what you would suggest for an intinerary. We do like RC but are willing to try others for this cruise. Even 30 days would be ok (if the back pocket doesn't get hit too hard). Thanks in advance for your help.

Hanna, having just completed the Hawaii & Tahiti course at Princess Academy, theirs is fresh in my mind.

Princess has a 31 day Hawaii, Tahiti & South Pacific cruise from San Francisco to Sydney, Australia. The only itinerary I have for Princess is September, 2008, with 13 ports and 2 departures on the Dawn Princess.
San Francisco,
At Sea
Honolulu, Hi
Kona, Hi
At Sea
Christmas Island, Kiribati
At Sea(Cross the equator)
Bora Bora, French Polynesia
Tahiti, French Polynesia(Papeete)
Moorea, French Polynesia
At Sea
Rarotonga, Cook Islands
At Sea
Pago Pago, American Samoa
At Sea(Cross the Int'l Dateline)
Fiji, Suva
At Sea
Auckland, New Zealand
At Sea
Wellington, New Zealand
Christchurch, New Zealand(Lyttelton)
Dunedin, New Zealand(Port Chalmers)
Fjordland Nat'l Park, New Zealand(scenic cruising)
At Sea
Sydney, Australia.
(I know you won't sail this year)

Just found this: The following 30 day itinerary on the Star Princess is available on the Sept. 30, 2009 sailing(1 departure):

Holland America has a 30 day Hawaii, Tahiti, Marquesas Islands itinerary on the MS Ryndam from San Diego on Jan 4 2009. Crystal Cruises, a luxury line also has itineraries but you are looking at far higher prices.

This is directly from a travel site concerning when is the best time to visit Tahiti:

When is the best time to visit Tahiti?

Actually, it depends on what you want to do and to see in Tahiti and her islands. The climate is devided into two main seasons : a wet season between November and March and a dry season from April to October .

The wet season is characterized by a warmer and more humid weather. But obviously, the lagoon temperatures are also higher, there are huge rollers to surf, you can attend “springtime” for nature…

The dry season is characterized by a cooler and less humid weather with some sporadic short rains that are often welcomed since droughts and water rationing may appear in some islands. During this period, the underwater visibility is the best for scuba diving, humpback wales are migrating from Antartica and make a stop in our waters. The very famous Heiva (traditional festival) is also organized during this period.

Obviously, as the climate is tropical, rain may appear at every moment of the year and besides, since the Polynesian islands are spread over a surface of 4,000,000 km², the temparatures and humidity are very different from one archipelago to another.

As for ships, you might want to take a look at the Celebrity Millennium - it's only a 15-day one-way cruise, but a very nice ship.

For a longer cruise, take a look at the Sun Princess - goes from Sydney to San Francisco by way of Tahiti and Hawaii or the Dawn Princess doing the reverse.

The Holland America Statendam goes roundtrip from San Diego via Hawaii and Tahiti on a 30-day odyssey, which I think is one of the nicest options.

You could think about doing a one-way cruise, in which case you'd have to fly one-way, which is not a cheap flight depending on where you're flying into or out of. Or you could do two one-way cruises either on the same cruise line or perhaps two different cruise lines if the dates work out. Or you could do a roundtrip from the U.S. and spend alot of days at sea. Many things to consider.

There are some other cruises, but perhaps this will give you some ideas. There are also other cruise lines, such as Regent and Seabourn, but the prices are considerably higher.